having its origin far to the north and pushing its edge slowiv 

 outward like j vast gob of molasses. To the contrary, a chanRf 

 of climate that caused winter snows on the Laurentian Shield to 

 accumulate without melting in summer could have started the 

 process: or excessive snow could have blanketed the whole 

 country Then, if the snow did not melt, it would be converted 

 to an ever increasing mass of firn that finally compacted to ice. 

 which, growing in thickness, would eventually initiate those 

 movements mentioned above. The edge or front of the cap may 

 m fact not have moved at all although enormous volumes of ice 

 moved outward from the inner areas of the cap to its periphery. 

 In either case, the movement was massive and produced most 

 noticeable effects. 



The first of these was that the entire surface of the earth was 

 bulldozed, not only of all vegetation and surface soil but of 

 subsoil and, where the land rose above the general level, of 

 whole hills. Whether the ice formed in situ or flowed in from 

 outside, it froze everything beneath it unto itself in one vast 

 permafrost, with the result that the bottom of the ice mass 

 consisted not so much of ice but of all manner of rock fragments, 

 from boulders weighing hundreds of tons to fine sediment, like 

 the abrasive granules on a monstrous sheet of sandpaper. As 

 this was shoved over the face of the earth it ground everything 

 flat, while itself being fractionated; and one may gain some 

 idea of the power of this abrasive machine by calculating the 

 downward pressure exerted by two miles of ice. This works out 

 at about nine billion tons per square mile of land surface. The 

 ancient Egyptians cut the enormous blocks of stone to build their 

 pyramids with saws made of soft copper or even of wood, simply 

 by moving sand and water bade and forth in grooves under their 

 modest weight. The really remarkable thing is that anything 

 except a sort of rock soup should remain under the terrific 

 pressure of the ice. 



Vast quantities of such "soup" were produced, whidi finally 

 seeped out from under the edge of the ice or were left after it 

 melted. This was washed away by the meltwater and deposited 

 in lakes and swamps, or at the bottom of the seas and oceans, as 

 extremely finely particulated silts. The highly stidcy clays that 

 cover large areas of the surface of Canada, the Yukon, and 

 Alaska today are composed of this material. A lot of coarser 

 material also survived, ranging all the way from fine sand to 

 enormous boulders. These have all their corners rounded off, 

 and when they are deposited along with clay, sand, and other 

 materials, and compacted, they form a monumental hodgepodge 

 or "conglomerate," as it is so aptly called by geologists. Con- 

 siderable areas on the land surface of this province are covered 

 with this ground-up and rolled material left by the ice. Where 

 the land surface was mountainous enough to cause the ice to 

 break up into separate tongues between the peaks, moraines 

 were formed on top of the sheet. These are long lines of broken 

 rock, gouged out of or knocked oflF the containing mountain 

 sides, or fallen down upon the ice surface from above due to 

 frost action. These snaking lines of material are then carried 

 forward on top of the ice and finally dumped off the front of the 

 icecap. Sometimes, however, this material sinks down into the 

 ice and gets carried along in its midst, or it works its way right 

 to the bottom and gets ground up along with the other material 

 down there. If it stays on top of the ice it may be dumped 

 without having been rolled; it is then readily recognizable due 

 to the angular edges of its component rocks. 



In addition to these various types of moraines left at the edge 

 of the icecap (which result in typical country sudi as is seen 

 over the greater part of the north of this province, with hum- 

 modcy low hills scattered in haphazard manner and with de- 



A tree frog, or tree toad (Hyla). Billions of these inhabit 

 temperate and tropical areas. They have clinging disks on 

 their toes, are adept tree-climbers, and eat insects. 



pressions between them from which there is no outlet), the ice 

 left other distinctive things. Two of these are drumlins and 

 eskers. The former are also isolated low hills, but they have one 

 longer axis and they lie in roughly parallel lines, these lines 

 following the direction of the retreat of the ice so that they 

 slowly converge upon its final point of departure. The method 

 of their formation is not known; nor is that of the strange eskers. 

 These are long, narrow banks, looking for all the world like 

 abandoned railroad beds, that may run perfectly straight for 

 miles or wander about like vast snakes One suggestion as to 

 their origin is that they were formed in long, tunnel-like caves 



85 



